Heretofore, polyimide-based and polybenzoxazole-based resins having excellent heat resistance and electrical insulation properties have widely been used in a surface protective film and an interlayer dielectric film of semiconductor devices, an insulating layer of organic electroluminescence elements, and a flattened film of TFT substrates. In addition, in order to enhance productivity, a photosensitive polyimide and a photosensitive polybenzoxazole have been considered. However, they are much reduced in the form of a film during development and are much affected by an environment in which they are used, and it has been pointed out that they are difficult to use in industry.
In addition, a photosensitive resin composition containing a polyimide having an alkoxymethyl group and a compound having 2 or more alkoxymethyl groups or methylol groups (Patent Literature 1), a positive-working photosensitive resin composition containing a polyhydroxystyrene resin and a compound having an alkoxymethyl group or a methylol group (Patent Literature 2), and a photosensitive resin composition in which a specific amount of an isocyanuric acid derivative having a specific structure is added to a polyhydroxyamide having a specific structure (Patent Literature 3) have been proposed, and have achieved an increased sensitivity and a lowered stressfulness. In recent years, however, the increasing degree of integration of semiconductor devices has been accompanied by a demand for the reduction of heat load on semiconductor devices in production processes and further by a demand for the reduction of the warpage caused to a substrate wafer by a thicker film of an insulating material, but the above-described materials cause a large film shrinkage after high temperature baking, generate a high stress to a substrate wafer, and thus increase the warpage of a substrate material, posing a problem, which remains to be solved adequately.
Proposed for this is a method in which a flexibility group is introduced into a repeating unit of an alkali-soluble cyclized polyimide or polybenzoxazole, whereby stress generated in producing a cured film is suppressed to achieve a lower warpage (Patent Literature 4).